Cost-effective transport of district heat for developing combined heat and power
|Location||MVV Energie AG, 68159 Mannheim, Baden-Württemberg, Germany|
|Project plan||The focus of the work is on structural- and pipe-based developments to large-scale pipelines. For this purpose, experimental investigations are being conducted in a laboratory and technical lab whose findings will be directly applied in practice, i.e. tested on demonstration building sites. The technical lab investigations are scheduled to be completed in 2012. The field trials are due to be completed in 2013.|
|Developer, organizer||BMWi and MVV Energie AG|
The costs for district heating including delivery to customers are dominated by the proportion of costs allocated for generating, distributing and transferring the heat to customers. The costs for transporting heat at the point where it is currently realised makes up a comparatively low proportion. Transporting district heating, however, also enables heat from particularly efficient and cost-effective large-scale CHP plants to be used for providing district and local heating in more remote areas. This enables the operating range of the district heating to be expanded, which in large-scale plants can be generated with considerably lower specific investments and operating costs.
The aim of the project is to make use of co-generation heat from particularly effective large-scale plants in areas where heat was previously generated in less effective and particularly expensive units. A further aim is to reduce the costs for constructing pipelines for transporting district heating by means of planning, structural and constructional further developments, whereby the aim is to reduce these costs by about 10 to 15%. The research work comprises 4 work packages (WP):
- WP1 – Study on the theme of “heat transport in competition for decentralised heat generation”
- WP2 – Cross-sectional study on transporting district heat (pipeline technology, further development, savings potential)
- WP3 – Constructional developments
- WP4 – Manual: “Measures for minimising costs when constructing pipelines for transporting district heating”
Economic heat transport reaches its limits where the costs for generating heat in large-scale CHP plants plus the transport expenditure are commensurate with the costs for generating heat in small-scale systems. Since the investments in the pipelines cause the largest costs, it makes sense to reduce their construction costs. To achieve this, interesting approaches are being pursued that are offered in both civil engineering and pipeline construction. These include technical and economic investigations in the form of a study on the limits of transporting heat and, on the other hand, constructional developments relating to pipeline technology and civil engineering. In terms of the pipeline technology, the introduction of the so-called cold laying method for plastic composite pipes is also being investigated for large-scale lines and, in civil engineering, an effort is being made to reuse excavated material and, after processing it to form a casting compound, to install it again in free-flowing form.
Construction costs are reduced by avoiding both landfill costs and the procurement of new material. Further savings can be achieved in terms of the road construction. The further development of the cold laying method in pipeline construction will simplify the construction process.
The study on the economic feasibility will provide guidance in determining the limits for transporting district heating and thus whether to opt for centralised or decentralised district heating generation.
Technical solutions are being planned and implemented as part of field trials being conducted on the Mannheim-Speyer district heating main transmission line and the Lindenhof district heating trunk line. Initial trials concerned with casting connections and adapting the pipeline statics were successfully carried out on the Mannheim–Speyer transport connection in 2010 and 2011. Further field trials are currently undergoing detailed design for construction measures planned in the Mannheim metropolitan area (trunk line).
For the sequence of work it is important that the laboratory tests are coordinated with the field trials, since the scientific investigations being conducted by the Fernwärme-Forschungsinstitut Hannover and Regensburg University of Applied Science are intended to provide decisive information on laying pipelines. The laboratory tests are scheduled to be completed in 2012 so that the field trials can then be completed in the following year. The field trials are a major restraint on the heat supply company, since the construction of a major pipeline always represents a special construction measure.
The study (WP1), which is investigating the possibilities for economically transporting district heating, is being conducted as an accompanying measure. It is also aimed at determining the extent to which reducing the pipeline construction costs through utilising advanced construction technology can also economically extend the limits for supplying district heating.
Schmitt, F.; Caspar, J.; Grage, T.; Liebermann, A.: Verlegung von KVMR-Leitungen ohne mechanische Verdichtung mit Vergussmassen. EuroHeat&Power 41. Jg. (2012), Heft 11, S. 44 - 49.